There is an unusable emoticon (I am displaying it here using the [/img] tag). First page, fifth from the end: the big, red grinning devil:

There are three devil icons on that first page:
The first one is located at http://forums.realgm.com/boards/images/smilies/icon_evil.gif, and inserts the code ":evil:" -

The second is located at http://forums.realgm.com/boards/images/smilies/devil.gif, and inserts ":devil:" -

The third is located at http://forums.realgm.com/boards/images/smilies/icon__2.gif, and also inserts ":devil:", which then displays the 2nd emoticon -


I haven't been able to identify a code that will actually insert the third devil.
:devil1:
:devil2:
:devil_2:
:devil__2:
:2:
:_2:
:__2:
:icon__2: